Turbine disk

ABSTRACT

A turbine rotor disk for a gas turbine engine includes a disk rotationally disposed about a central axis. The disk includes a number of blade posts, tabs and slots circumferentially disposed about a rim portion of the disk. The tabs each include a blade post transition portion, a slope portion radially inward of the blade transition portion and a face portion radially inward of the slope portion. The blade posts, tabs and slots are circumferentially oriented about the rim portion such that a tab or slot is positioned radially inward of each blade post.

FIELD

The present disclosure relates to turbine engines and, moreparticularly, to rotors and rotor disks used in turbine engines.

BACKGROUND

Gas turbine engines, such as those utilized in commercial and militaryaircraft, include a compressor that compresses air, a combustor thatmixes the compressed air with a fuel and ignites the mixture, and aturbine that expands the resultant gases from the combustion. Theexpansion of the gases through the turbine drives rotors within theturbine (referred to as turbine rotors) to rotate. The turbine rotorsare connected to a shaft that is connected to rotors within thecompressor (referred to as compressor rotors), thereby driving thecompressor rotors to rotate.

In some gas turbine engines, or sections of some gas turbine engines,the rotors are exposed to significant temperatures. For example, inturbine sections, the resultant gases from the combustion process exposethe turbine disks and, particularly, the rim portions of the turbinedisks, to highly elevated temperatures. Combined with repeatedacceleration and deceleration associated with normal operation, thedisks may experience low cycle fatigue or thermal mechanical fatigue.Discontinuities in disk geometries may exacerbate the onset of suchfatigue.

SUMMARY

In various embodiments, a turbine rotor for a gas turbine engineincludes a disk rotationally disposed about a central axis that includesa first radially outermost rim portion and a second radially outermostrim portion. The second radially outermost rim portion is disposedradially inward of the first radially outermost rim portion. The rotorfurther includes a first blade post disposed proximate the firstradially outermost rim portion and a first tab disposed proximate thesecond radially outermost rim portion. The tab is positioned radiallyinward of the first post and has a first axial profile. The first axialprofile includes a blade post transition portion, a slope portionradially inward of the blade transition portion and a face portionradially inward of the slope portion.

In various embodiments, the first blade post has a tip and a base andthe blade post transition portion of the first tab is disposed at alocation between the tip and the base. In various embodiments, the tipand the base of the first blade post defines a length in the radialdirection and the blade post transition portion is disposed at alocation between about 25% and about 50% of the length in the radiallyoutward direction. Various embodiments contemplate the blade posttransition portion having a radius of curvature of about 0.100 inches toabout 0.300 inches. In various embodiments, the first blade postincludes one or more branches spaced radially between the base and thetip and the blade post transition portion is disposed proximate theradially most inward branch.

In various embodiments, the slope portion of the first tab extendsradially inward from the blade post transition portion. In variousembodiments, the slope portion of the first tab extends radially inwardfrom the blade post transition portion at an angle with respect to acentral axis and the slope portion merges with the face portion. Invarious embodiments, the slope portion extends radially inward at anangle of about 60 degrees to about 65 degrees with respect to thecentral axis. In various embodiments, the slope portion extends radiallyinward at an angle of about 60 degrees to about 65 degrees with respectto the central axis and the face portion extends radially inward at anangle of about 85 degrees to about 95 degrees with respect to thecentral axis.

In various embodiments, the rotor also includes a second blade postdisposed circumferentially adjacent the first blade post and a secondtab disposed circumferentially adjacent the first tab. The second tab ispositioned radially inward of the second post and has a second axialprofile identical in shape to the first axial profile. A slot may alsobe disposed between the first tab and the second tab.

Another embodiment of a turbine rotor includes a disk rotationallydisposed about a central axis and a plurality of blade posts disposed onand spaced circumferentially about a radially outermost portion of thedisk. A plurality of tabs is also disposed on and spacedcircumferentially about a portion of the disk radially inward from theradially outermost portion of the disk. An axial profile of each of tabsincludes a blade post transition portion, a slope portion radiallyinward of the blade transition portion and a face portion radiallyinward of the slope portion.

In various embodiments, the blade posts have a tip and a base and theblade post transition portions of the tabs are disposed at a locationbetween the tip and the base. In some embodiments, the slope portionsextend radially inward from the blade post transition portions at anangle with respect to a central axis and the slope portions merge withthe face portions.

In various embodiments, the blade post transition portions have a radiusof curvature of about 0.100 inches (2.54 mm) to about 0.300 inches (7.62mm). In various embodiments, the slope portions extend radially inwardat an angle of between about 60 degrees and about 65 degrees withrespect to the central axis. In various embodiments, the slope portionsextend radially inward at an angle of about 62 degrees with respect tothe central axis and each corresponding face portion extends radiallyinward at an angle of about 90 degrees with respect to the central axis.In various embodiments, a slot is disposed radially inward ofalternating blade posts. A slot may also be disposed radially inward ofeach one of the plurality of blade posts.

In another embodiment, a turbine rotor includes a disk rotationallydisposed about a central axis. A plurality of blade posts is disposed onand spaced circumferentially about a radially outermost portion of thedisk. A plurality of tabs is also disposed on and spacedcircumferentially about a portion of the disk radially inward from theradially outermost portion of the disk. A plurality of slots is alsointerspersed between adjacent pairs of tabs. An axial profile defined byof the plurality of tabs includes a blade post transition portion, aslope portion merging with and extending radially inward of the bladepost transition portion and a face portion merging with and extendingradially inward of the slope portion.

In various embodiments, the blade post transition portions have a radiusof curvature of about 0.100 inches (2.54 mm) to about 0.300 inches (7.62mm), the slope portions extend radially inward at an angle of about 60degrees to about 65 degrees with respect to a central axis and the faceportions extend radially inward at an angle of about 85 degrees to about95 degrees with respect to the central axis.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments employing theprinciples described herein and are a part of the specification. Theillustrated embodiments are meant for description and do not limit thescope of the claims.

FIG. 1 is a schematic view of a gas turbine engine, in accordance withvarious embodiments;

FIG. 2 is a schematic view of a turbine assembly, in accordance withvarious embodiments;

FIG. 3 is a schematic view of a rotor and seal assembly, in accordancewith various embodiments;

FIG. 4 is a schematic view of a rim section of a disk, in accordancewith various embodiments;

FIG. 5 is a cross sectional view of a rim and web section of a disk, inaccordance with various embodiments;

FIG. 6 is a cross sectional view of a turbine disk, in accordance withvarious embodiments; and

FIG. 7 is a cross sectional view of a rim and web section of a disk, inaccordance with various embodiments.

DETAILED DESCRIPTION

All ranges may include the upper and lower values, and all ranges andratio limits disclosed herein may be combined. It is to be understoodthat unless specifically stated otherwise, references to “a,” “an,”and/or “the” may include one or more than one and that reference to anitem in the singular may also include the item in the plural.

The detailed description of various embodiments herein makes referenceto the accompanying drawings, which show various embodiments by way ofillustration. While these various embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosure, it should be understood that other embodiments may berealized and that logical, chemical, and mechanical changes may be madewithout departing from the scope of the disclosure. Thus, the detaileddescription herein is presented for purposes of illustration only andnot of limitation. Furthermore, any reference to singular includesplural embodiments, and any reference to more than one component or stepmay include a singular embodiment or step. Also, any reference toattached, fixed, connected, or the like may include permanent,removable, temporary, partial, full, and/or any other possibleattachment option. Additionally, any reference to without contact (orsimilar phrases) may also include reduced contact or minimal contact.

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmenter section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flow path B in abypass duct defined within a nacelle 15, while the compressor section 24drives air along a core or primary flow path C for compression andcommunication into the combustor section 26 and then expansion throughthe turbine section 28. Although depicted as a two-spool turbofan gasturbine engine in the disclosed non-limiting embodiment, it should beunderstood that the concepts described herein are not limited to usewith two-spool turbofans as the teachings may be applied to other typesof turbine engines, including three-spool architectures.

The gas turbine engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems 38 at various locations may alternatively or additionally beprovided and the location of the bearing systems 38 may be varied asappropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a first (or low) pressure compressor 44 and afirst (or low) pressure turbine 46. The inner shaft 40 is connected tothe fan 42 through a speed change mechanism, which in this gas turbineengine 20 is illustrated as a geared architecture 48 to drive the fan 42at a lower speed than the low speed spool 30. The high speed spool 32includes an outer shaft 50 that interconnects a second (or high)pressure compressor 52 and a second (or high) pressure turbine 54. Acombustor 56 is arranged in the gas turbine engine 20 between the highpressure compressor 52 and the high pressure turbine 54. A mid-turbineframe 57 of the engine static structure 36 is arranged generally betweenthe high pressure turbine 54 and the low pressure turbine 46. Themid-turbine frame 57 further supports the bearing systems 38 in theturbine section 28. The inner shaft 40 and the outer shaft 50 areconcentric and rotate via the bearing systems 38 about the enginecentral longitudinal axis A, which is collinear with their longitudinalaxes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The mid-turbine frame 57 includes airfoils 59 thatare in the core airflow path C. The low and high speed turbines 46, 54rotationally drive the respective low speed spool 30 and high speedspool 32 in response to the expansion. It will be appreciated that eachof the positions of the fan section 22, compressor section 24, combustorsection 26, turbine section 28, and fan drive gear system 48 may bevaried. For example, the gear system 46 may be located aft of thecombustor section 26 or even aft of the turbine section 28, and the fansection 22 may be positioned forward or aft of the location of the gearsystem 48.

The engine 20 in one embodiment is a high-bypass geared aircraft engine.In a further embodiment, the engine 20 bypass ratio is greater thanabout six (6), with one embodiment being greater than about ten (10),the geared architecture 48 is an epicyclic gear train, such as aplanetary gear system or other gear system, with a gear reduction ratioof greater than about 2.3 and the low pressure turbine 46 has a pressureratio that is greater than about five. In one disclosed embodiment, theengine 20 bypass ratio is greater than about ten (10:1), the fandiameter is significantly larger than that of the low pressurecompressor 44, and the low pressure turbine 46 has a pressure ratio thatis greater than about five 5:1. A low pressure turbine 46 pressure ratiois the pressure measured prior to inlet of the low pressure turbine 46as related to the pressure at the outlet of the low pressure turbine 46prior to an exhaust nozzle. It should be understood, however, that theabove parameters are descriptive of only one embodiment of a gearedarchitecture engine and that the present invention is applicable toother gas turbine engines, including direct drive turbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition typically cruise at about 0.8 Mach andabout 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft(10,668 meters), with the engine at its best fuel consumption—also knownas “bucket cruise Thrust Specific Fuel Consumption (“TSFC”)”—is theindustry standard parameter of lbm of fuel being burned divided by lbfof thrust the engine produces at that minimum point. “Low fan pressureratio” is the pressure ratio across the fan blade alone, without a FanExit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosedherein according to one non-limiting embodiment is less than about 1.45.“Low corrected fan tip speed” is the actual fan tip speed in ft/secdivided by an industry standard temperature correction of [(Tram °R)/(518.7° R)]̂0.5. The “Low corrected fan tip speed” as disclosed hereinaccording to one non-limiting embodiment is less than about 1150ft/second (350.5 meters/second).

With continued reference to FIG. 1, and with like numerals indicatinglike elements, FIG. 2 illustrates schematically a turbine section, suchas a high pressure turbine assembly 54, while FIG. 3 illustratesschematically a close up view of a rotor and seal assembly 68. The highpressure turbine assembly 54 includes a first rotor 34 and a secondrotor 35, with the second rotor 35 disposed aft (or downstream) of thefirst rotor 34. The second rotor 35 generally includes a bore (see,e.g., 304 at FIG. 6), a web 70 radially outward of the bore and a rim 72radially outward of the web 70. The bore, web 70 and rim 72 extendcircumferentially about the engine central longitudinal axis A andcollectively comprise a rotor disk or turbine disk 37. The second rotor35 includes an aft surface 62 and a forward surface 64. The second rotor35 further includes a plurality of blades 66 spaced circumferentiallyabout and connected to the rim 72. In various embodiments, the blades 66are connected to the rim 72 using attachment sections (not shown)disposed at the base of the blades that are received within bladeretention slots (see, e.g., 136 at FIG. 4) positioned within the rim 72.The attachment sections (or blade roots) and the blade retention slotscan have various contours, including, for example, dove-tail, fir-treeor bulb type contours. In other embodiments, the blades 66 are formedintegrally with the rim 72. While the above description has focused onthe second rotor 35, the same general characteristics apply to the firstrotor 34.

Referring still to FIGS. 2 and 3, the rotor and seal assembly 68includes an annular platform 80 that extends circumferentially about theengine central longitudinal axis A. The annular platform 80 includes abase 82 that interfaces with an outer portion 73 of the rim 72. The base82 houses a seal 84 that prevents hot gases flowing in the core airflowpath C from leaking into the disk region of the rotor 35. The annularplatform further includes an arm 86 and hook 88. In various embodiments,the arm 86 extends generally in a radial direction while the hook 88extends generally in the axial direction. The hook 88 includes an uppersurface 90 that is sized and configured to slidably engage a tab portion92 of the rim 72. The tab portion 92 includes a lower surface 94 thatmatches the upper surface 90 of the hook 88. As described in thesections that follow, the tab portion 92 may, in various embodiments,comprise a plurality of tabs interspersed with or separated by aplurality of slots, both the tabs and slots extending circumferentiallyabout the rim 72 of the disk 37 or rotor 35. Still referring to FIG. 3,the rotor and seal assembly 68 further includes a second annularplatform 96 disposed aft of the rim 72. The second annular platform 96includes a base 97 that interfaces with an outer portion 93 of the rim72. The base 97 houses a seal 98 that prevents hot gases flowing in thecore airflow path C from leaking into the disk region of the rotor 35.

Referring now to FIG. 4, a portion of a rotor disk 200 is illustrated,exhibiting various features of the present disclosure. The rotor disk200 includes a web portion 202 and rim portion 203. The rim portion 203includes a plurality of radially extending blade posts 208 that eachincludes one or more circumferentially extending branch elements 230.The branch elements 230 positioned on adjacent blade posts 208 are sizedand configured to secure corresponding attachment sections of individualrotor blades. Each blade post 208 generally includes a tip 222, a base224 a forward facing surface 240 and an aft facing surface 242. Invarious embodiments of the present disclosure, the forward facingsurface 240 may have a first portion 250 that extends radially inwardfrom the tip 222 to a blade post transition portion 216, positioned in aregion between the tip 222 and the base 224. In various embodiments, theblade post transition portion 216 may be positioned or disposed at alocation between about 25% and 50% of the length between the tip 222 andthe base 224 in a radially outward direction from the base 224. Invarious embodiments, the blade post transition portion 216 may bepositioned or disposed proximate a radially-most inward one of thebranch elements 230. The forward facing surface 240 may further includea slope portion 218 that extends radially inward from the bladetransition portion 216 toward the base 224. In various embodiments, theslope portion 218 also extends axially in the forward direction, thusproviding a slope or a face with a surface normal that resides at anon-zero angle with respect to an axial direction 226 of the rotor disk200.

Still referring to FIG. 4, a plurality of tabs 210 is spacedcircumferentially about the rim portion 203. A slot 214 is positionedbetween adjacent pairs of tabs 210, providing a plurality of slots 214circumferentially spaced about the rim portion 203. In variousembodiments, a tab 210 is positioned, generally, radially inward ofevery other (e.g., odd numbered, counting circumferentially) blade post208. Similarly, a slot 214 is positioned, generally, radially inward ofthe remaining (e.g., even numbered) blade posts 208. Positioning thetabs 210 with respect to the blade posts 208 in such manner provides an“in-phase” relation between the positioning of the tabs 210 (and theslots 214) and the blade posts 208. The “in-phase” relation contrastswith embodiments where there is no clear phase relation between thecircumferential positioning of tabs with respect to the circumferentialpositioning of the blade posts—e.g., embodiments where some tabs arepositioned radially inward of blade posts while other tabs arepositioned radially inward of troughs between adjacent blade posts whilestill other tabs are positioned radially inward of a portion of a troughand a portion of a blade post adjacent the through. Thus, in variousembodiments of the present disclosure, the number of tabs (N_(Tabs))will equal the number of slots (N_(Slots)), while both N_(Tabs) andN_(Slots) will equal one-half the number of posts (N_(Posts)). Invarious embodiments, N_(Tabs)=N_(Slots)=41 and N_(Posts)=82. In variousembodiments, each tab 210 may have a circumferential length 252 and eachslot 214 may have a circumferential length 254. In addition, in variousembodiments, the circumferential length 252 of each tab 210 may be aboutthe same as the circumferential length 254 of each slot 214. In variousembodiments, the circumferential length 252 of each tab 210 may begreater than or less than the circumferential length 254 of each slot214. In various embodiments, the circumferential length 254 of each slot214 has a value within a range from about 0.900 inches (22.86 mm) toabout 0.950 inches (24.13 mm). In various embodiments, thecircumferential length 254 of each slot 214 has a value within a rangefrom about 0.910 inches (23.11 mm) to about 0.930 inches (23.62 mm) andN_(Tabs)=N_(Slots)=41.

Referring now to FIGS. 4 and 5, various geometries for the tabs 210,slots 214 and forward facing surfaces 240 with respect to the rimportion 203 are described. As stated above, the forward facing surface240 of each blade post 208 includes a first portion 250 that extendsradially inward from the tip 222 to a blade post transition portion 216,positioned in a region between the tip 222 and the base 224. The forwardfacing surface 240 may further include a slope portion 218 that extendsradially inward from the blade transition portion 216 toward the base224. In various embodiments, the slope portion 218 may extend beyond thebase 224 to intersect with a face portion 220 of a tab 210. Intersectionof the slope portion 218 with a face portion 220 typically occurs wherea tab 210 is disposed radially inward of a post 208, as illustrated inFIG. 4. In various embodiments, the face portion 220 of each tab 210extends radially inward at an angle of about 85 degrees to about 95degrees with respect to the longitudinal axis of the rotor disk 200 orthe engine central longitudinal axis A. In various embodiments, the faceportion 220 extends radially inward at an angle of about 90 degrees withrespect to the longitudinal axis of the rotor disk 200. In other words,at an angle of 90 degrees, the face portion 220 defines a surface thatis normal (i.e., perpendicular) to the central longitudinal axis A.

Still referring to FIGS. 4 and 5, the forward facing surface 240 of eachblade post 208, including the first portion 250, the blade transitionportion 216 and the slope portion 218 defines an axial profile. Forblade posts 208 having a tab 210 positioned radially inward of the base224, the axial profile will include the face portion 220 of the tab 210.For blade posts 208 having a slot 214 positioned radially inward of thebase, the axial profile will terminate at the radially outermost part ofthe slot. The axial profile may include sub-profiles. For example, theaxial profile may include a first axial profile extending from the bladetransition portion 216 to the face portion 220 of a tab 210 andincluding the slope portion 218. Generally, the blade posts arepositioned in a first radially outermost rim portion 204 while the tabs210 and slots are positioned in a second radially outermost rim portion206. The second radially outermost rim portion 206 resides radiallyinward of the first radially outermost rim portion 204.

In various embodiments, the blade transition portion 216, the slopeportion 218 and the face portion 220 may be defined through specifiedgeometrical values. For example, referring primarily to FIG. 5, theblade transition portion 216 may include a radius of curvature 260. Invarious embodiments, the radius of curvature 260 may have values rangingfrom about 0.100 inches (2.54 mm) to about 0.300 inches (7.62 mm). Invarious embodiments, the radius of curvature may range from about 0.194inches (4.92 mm) to about 0.214 inches (5.43 mm). In variousembodiments, the radius of curvature 260 may be specified to have avalue of about 0.204 inches (5.18 mm). Similarly, the slope portion 218may be defined by a slope angle 262. In various embodiments, the slopeangle 262 may have a value of about 60 degrees to about 65 degrees, withthe angle defined as extending radially inward from an axial direction.In various embodiments, the slope angle 262 may range from about 61.5degrees to about 62.5 degrees. In various embodiments, the slope angle262 may be specified to be about 62 degrees. The geometry of the slots214 may also be defined by geometrical values. For example, each slot214 may include a roof portion 231 that is defined by a roof angle 264.In various embodiments, the roof angle 264 may range from about 35degrees to about 45 degrees, with the angle defined as extendingradially outward from an axial direction. In various embodiments, theroof angle 264 may range from about 39.5 degrees to about 40.5 degrees.In various embodiments, the roof angle 264 may be specified to be about40 degrees. In various embodiments, a radial length 272 between theblade transition portion 216 and a radially outermost point 274 of theface portion 220 of each tab 210 has a value within a range of about0.590 inches (14.98 mm) to about 0.600 inches (15.24 mm). In variousembodiments, an axial length 275 between the first portion 250 of theblade posts 208 and the face portion 220 of the tabs 210 has a valuewithin a range of about 0.290 inches (7.36 mm) and about 0.300 inches(7.62 mm).

Referring now to FIG. 6, a cross sectional view of a turbine disk 300,in accordance with various embodiments is illustrated. The turbine disk300 includes a rim portion 302 and a bore portion 304. A web portion 306is disposed radially between the rim portion 302 and the bore portion306. In various embodiments, each of the rim portion 302, the boreportion 304 and the web portion 306 is annular about a central axis 308.The web portion 306 may include a fore surface 310 and an aft surface312. The turbine disk 300 may further include a cylindrical arm 314disposed on and intersecting the aft surface 312. The cylindrical arm314 may include a first portion 316 that extends generally in an axialdirection from the aft surface 312. A second portion 318 of thecylindrical arm 314 extends radially outward from a distal end 317 ofthe first portion 316. In various embodiments, the cylindrical arm 314may be axisymmetric about the central axis 308. In various embodiments,the cylindrical arm 314 may comprise a plurality of segments spacedcircumferentially about the central axis 308, with spaces or slotspositioned between adjacent segments. The intersection of thecylindrical arm 314 with the aft surface 312 of the web portion 306 maydefine a fillet 320 radially inward of the first portion 316 of thecylindrical arm 314.

In various embodiments, the fillet 320 may comprise a compound fillet322. For example, with continued reference to FIG. 6, and with likenumerals indicating like elements, FIG. 7 provides a cross sectionalclose-up view of a compound fillet 322, in accordance with variousembodiments, near the rim portion 302 of the turbine disk 300. Invarious embodiments, the compound fillet 322 may be defined by acompound radius, which may include a minor radius 324 and a major radius326. In various embodiments, the minor radius 324 is defined by a minorradius of curvature having a range from about 0.190 inches (4.82 mm) toabout 0.220 inches (5.58 mm) and the major radius 326 is defined by amajor radius of curvature having a range from about 4.400 inches (111.76mm) to about 4.600 inches (116.84 mm). In various embodiments, the minorradius 324 is defined by a minor radius of curvature having a range fromabout 0.200 inches (5.08 mm) to about 0.210 inches (5.334 mm) and themajor radius 326 is defined by a major radius of curvature having arange from about 4.469 inches (113.51 mm) to about 4.531 inches (115.08mm).

In various embodiments, an axial value 340 of the origin of the minorradius 324 is positioned within an axial range from about 0.200 inches(5.08 mm) to about 0.240 inches (6.09 mm) aft of the aft surface 312. Invarious embodiments, a radial value 342 of the origin of the minorradius is also positioned within a radial range from about 0.200 inches(5.08 mm) to about 0.240 inches (6.09 mm) radially inward of a radiallyinward surface 344 of the first portion 316 of the cylindrical arm 314.In various embodiments, the axial value 340 of the origin of the minorradius 324 is positioned within an axial range from about 0.213 inches(5.41 mm) to about 0.223 inches (5.66 mm) aft of the aft surface 312. Invarious embodiments, the radial value 342 of the origin of the minorradius is also positioned within a radial range from about 0.213 inches(5.41 mm) to about 0.223 inches (5.66 mm) radially inward of theradially inward surface 344 of the first portion 316 of the cylindricalarm 314.

In various embodiments, an axial value 346 of the origin of the majorradius 326 is positioned within an axial range from about 4.400 inches(111.76 mm) to about 4.600 inches (116.84 mm) aft of the aft surface312. In various embodiments, a radial value 348 of the origin of themajor radius is also positioned within a radial range from about 0.400inches (10.16 mm) to about 0.480 inches (12.18 mm) radially inward ofthe radially inward surface 344 of the first portion 316 of thecylindrical arm 314. In various embodiments, the axial value 346 of theorigin of the major radius 326 is positioned within an axial range fromabout 4.469 inches (113.51 mm) to about 4.531 inches (115.08 mm) aft ofthe aft surface 312. In various embodiments, the radial value 348 of theorigin of the major radius is also positioned within a radial range fromabout 0.426 inches (10.82 mm) to about 0.446 inches (11.32 mm) radiallyinward of the radially inward surface 344 of the first portion 316 ofthe cylindrical arm 314. In various embodiments, the radial value 348 ofthe origin of the major radius 326 has a value equal to the radial value342 of the origin of the minor radius 324.

In various embodiments, the minor radius 324 intersects tangentiallywith the radially inward surface 344 of the first portion 316 of thecylindrical arm 314, thereby defining a first point of tangency 330. Invarious embodiments, the major radius 326 intersects tangentially withthe aft surface 312, thereby defining a second point of tangency 332. Invarious embodiments, the minor radius 324 and the major radius 326intersect tangentially with each other, thereby defining a third pointof tangency 334. In various embodiments, the third point of tangency 334defines a tangent plane that is tangent with the aft surface 312. Invarious embodiments, the minor radius 324 and the major radius 326 mayintersect non-tangentially with one another. In various embodiments,smoothing of the non-tangential intersection may occur in a smoothingregion 350 to remove sharp or discontinuous interfaces. Smoothingregions may also occur at the intersection of the minor radius 324 andthe radially inward surface 344 of the first portion 316 of thecylindrical arm 314 and at the intersection of the major radius 326 andthe aft surface 312 radially inward of the first portion 316 of thecylindrical arm 314.

Referring still to FIG. 6, the bore 304 is illustrated having a foresurface 360 and an aft surface 362. The aft surface 362 of the bore 304includes an aft web transition portion 364, an aft ramp portion 366 andan aft base transition portion 368. Likewise, the fore surface 360includes a fore web transition portion 370, a fore ramp portion 372 anda fore base transition portion 374. In various embodiments, the aft webtransition portion 364 and the fore web transition portion arepositioned at a radial length equal to about 14 inches (355.6 mm) toabout 15 inches (381 mm) from an axial center line or central axis 308.In various embodiments, either or both of the aft ramp portion 366 andthe fore ramp portion 372 have substantially linear profiles, meaningthe profiles have curvature radii greater than about 5 inches (127 mm).In various embodiments, the curvature radii may have values equal toabout 2 inches (50.8 mm) and in various embodiments the curvature radiimay range from about 2 inches (50.8 mm) to about 5 inches (127 mm). Invarious embodiments, either or both of the aft ramp portion 366 and thefore ramp portion 372 include linear segments between their respectiveweb and base transition portions. In various embodiments, the linearsegments may span the entire ramp portions. The aft base transitionportion 368 may include a face portion 376 that defines a surface normalpointing in a direction substantially parallel with the central axis308—e.g., within a range of angles from about 0 degrees (parallel) toabout 20 degrees, pointing radially outward from the central axis 308.In various embodiments, the face portion 376 defines a surface normalpointing in a direction parallel with the central axis 308.

In various embodiments, the aft web transition portion 364 may bedefined by a first radius of curvature that smoothly connects the aftsurface 312 of the web portion 306 and the aft ramp portion 366.Likewise, the fore web transition portion 370 may be defined by a secondradius of curvature that smoothly connects the fore surface 310 of theweb portion 306 and the fore ramp portion 372. In various embodiments,the first radius of curvature and the second radius of curvature areequal in value. The first and second radii of curvature may have valuesequal to about 2 inches (50.8 mm) in various embodiments, between about2 inches (50.8 mm) and about 5 inches (127 mm) in various embodimentsand greater than 5 inches (127 mm) in various embodiments.

In various embodiments, the web portion 306 further includes a baseportion 307. The base portion 307 may include a spool engagement surface380 and may further include a first arm 382 extending in the aftdirection and a second arm 384 extending in the fore direction. Invarious embodiments, the spool engagement surface 380 has a length 394within a range from about 3.6 (91.44 mm) inches to about 3.7 inches(93.98 mm). The base portion 307 may further include a radiallyextending first transition portion 386 connecting an aft end of thespool engagement surface 380 to a radially inward portion of the firstarm 382 and a radially extending second transition portion 388connecting a fore end of the spool engagement surface 380 to a radiallyinward portion of the second arm 384. The radially extending firsttransition portion 386 may include a first face portion 390 that definesa surface normal pointing in a direction substantially parallel with thecentral axis 308—e.g., within a range of angles from about 0 degrees(parallel) to about 20 degrees, pointing radially outward from thecentral axis 308. In various embodiments, the first face portion 390defines a surface normal pointing in a direction parallel with thecentral axis 308. Similarly, the radially extending second transitionportion 388 may include a second face portion 392 that defines a surfacenormal pointing in a direction substantially parallel with the centralaxis 308—e.g., within a range of angles from about 0 degrees (parallel)to about 20 degrees, pointing radially outward from the central axis308, but in a direction opposite that of the first face portion 390. Invarious embodiments, the second face portion 392 defines a surfacenormal pointing in a direction parallel with the central axis 308,though opposite that of the first face portion 390.

Various embodiments of the present disclosure are believed to provideimproved distributions of stress—e.g., axial, radial and hoop—throughoutthe turbine disk while tending to minimize local increases in weight toreduce maximum stress values occurring at discontinuities and regions ofhigh curvature. For example, adding weight to the rim portion near thetabs allows a reduction in maximum stress values through a reduction indiscontinuities and regions of high curvature. Similarly, adding weightto the bore region through use of substantially linear ramp portions orthe incorporation of base transition portions as described above providereductions in maximum stress values.

With reference to the foregoing illustrations, description andembodiments, the turbine rotors or turbine disks are described asdevices for utilization in a turbine section of a gas turbine engine.One of skill in the art, having the benefit of this disclosure, willunderstand that the disclosed rotors or disks can be utilized in otherstages or sections of a gas turbine engine. Furthermore, while describedabove within the context of a geared turbofan engine, one of skill inthe art will understand the above described rotor or disk can bebeneficially utilized in other turbine applications including, but notlimited to, direct drive turbine engines, land based turbines, andmarine turbines.

Finally, it is further understood that any of the above describedconcepts can be used alone or in combination with any or all of theother above described concepts. Although various embodiments have beendisclosed and described, one of ordinary skill in this art wouldrecognize that certain modifications would come within the scope of thisdisclosure. Accordingly, the description is not intended to beexhaustive or to limit the principles described or illustrated herein toany precise form. Many modifications and variations are possible inlight of the above teaching.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosure. The scope of the disclosure is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed:
 1. A turbine rotor, comprising: a disk rotationallydisposed about a central axis, the disk including a first radiallyoutermost rim portion and a second radially outermost rim portion, thesecond radially outermost rim portion disposed radially inward of thefirst radially outermost rim portion; a first blade post disposedproximate the first radially outermost rim portion; and a first tabdisposed proximate the second radially outermost rim portion, the firsttab positioned radially inward of the first post and having a firstaxial profile, wherein the first axial profile of the first tab includesa blade post transition portion, a slope portion radially inward of theblade transition portion and a face portion radially inward of the slopeportion.
 2. The turbine rotor of claim 1, wherein the first blade posthas a tip and a base and wherein the blade post transition portion ofthe first tab is disposed at a location between the tip and the base. 3.The turbine rotor of claim 2, wherein the tip and the base of the firstblade post defines a length in the radial direction and wherein theblade post transition portion is disposed at a location between about25% and about 50% of the length in the radially outward direction. 4.The turbine rotor of claim 3, wherein the blade post transition portionhas a radius of curvature of about 0.100 inches to about 0.300 inches.5. The turbine rotor of claim 2, wherein the first blade post includes aplurality of branches spaced radially between the base and the tip andwherein the blade post transition portion is disposed proximate theradially most inward branch.
 6. The turbine rotor of claim 2, whereinthe slope portion of the first tab extends radially inward from theblade post transition portion.
 7. The turbine rotor of claim 2, whereinthe slope portion of the first tab extends radially inward from theblade post transition portion at an angle with respect to the centralaxis and wherein the slope portion merges with the face portion.
 8. Theturbine rotor of claim 6, wherein the slope portion extends radiallyinward at an angle of about 60 degrees to about 65 degrees with respectto the central axis.
 9. The turbine rotor of claim 7, wherein the slopeportion extends radially inward at an angle of about 60 degrees to about65 degrees with respect to the central axis and wherein the face portionextends radially inward at an angle of about 85 degrees to about 95degrees with respect to the central axis.
 10. The turbine rotor of claim9, further comprising: a second blade post disposed circumferentiallyadjacent the first blade post; and a second tab disposedcircumferentially adjacent the first tab, the second tab positionedradially inward of the second post and having a second axial profileidentical in shape to the first axial profile; and a slot disposedbetween the first tab and the second tab.
 11. A turbine rotor,comprising: a disk rotationally disposed about a central axis; aplurality of blade posts disposed on and spaced circumferentially abouta radially outermost portion of the disk; and a plurality of tabsdisposed on and spaced circumferentially about a portion of the diskradially inward from the radially outermost portion of the disk, eachtab having an axial profile, wherein the axial profile of each one ofthe plurality of tabs includes a blade post transition portion, a slopeportion radially inward of the blade transition portion and a faceportion radially inward of the slope portion.
 12. The turbine rotor ofclaim 11, wherein the blade posts have a tip and a base and wherein theblade post transition portions of the tabs are disposed at a locationbetween the tip and the base.
 13. The turbine rotor of claim 12, whereinthe slope portions extend radially inward from the blade post transitionportions at an angle with respect to the central axis and wherein theslope portions merge with the face portions.
 14. The turbine rotor ofclaim 13, wherein the blade post transition portions have a radius ofcurvature of about 0.100 inches to about 0.300 inches.
 15. The turbinerotor of claim 14, wherein the slope portions extend radially inward atan angle of between about 60 degrees and about 65 degrees with respectto the central axis.
 16. The turbine rotor of claim 15, wherein theslope portions extend radially inward at an angle of about 62 degreeswith respect to the central axis and wherein each corresponding faceportion extends radially inward at an angle of about 90 degrees withrespect to the central axis.
 17. The turbine rotor of claim 11, whereina slot is disposed radially inward of alternating blade posts.
 18. Theturbine rotor of claim 11, wherein a slot is disposed radially inward ofeach one of the plurality of blade posts.
 19. A turbine rotor,comprising: a disk rotationally disposed about a central axis; aplurality of blade posts disposed on and spaced circumferentially abouta radially outermost portion of the disk; a plurality of tabs disposedon and spaced circumferentially about a portion of the disk radiallyinward from the radially outermost portion of the disk, each tab havingan axial profile; and a plurality of slots interspersed between adjacentpairs of tabs; wherein the axial profile of each one of the plurality oftabs includes a blade post transition portion, a slope portion mergingwith and extending radially inward of the blade post transition portionand a face portion merging with and extending radially inward of theslope portion.
 20. The turbine rotor of claim 19, wherein the blade posttransition portions have a radius of curvature of about 0.100 inches toabout 0.300 inches, wherein the slope portions extend radially inward atan angle of about 60 degrees to about 65 degrees with respect to thecentral axis and wherein the face portions extend radially inward at anangle of about 85 degrees to about 95 degrees with respect to thecentral axis.